I can't seem to cut and paste but here is the CAA's own AIC about the validity of theoretical exams:
http://www.caa.co.uk/docs/2026/EG_Ci...2011-08-11.pdf
Whilst it doesn't specifically talk about bridging credits, it does say that if all the exams conducted for the issue of a licence have been completed by the end of March then you will retain theory credit subject to the normal calendar validity restrictions. The CAA could easily argue the case that we haven't done all of the exams but, to me, it reads that the spirit of the rule is not to penalise those who have achieved theory credit prior to the changeover.